WO2023032135A1

WO2023032135A1 - Heat-removable pressure-sensitive adhesive tape

Info

Publication number: WO2023032135A1
Application number: PCT/JP2021/032343
Authority: WO
Inventors: 嶺木本; 翼森木; 衛一工藤; 太郎岩本; 靖史土屋
Original assignee: 株式会社寺岡製作所
Priority date: 2021-09-02
Filing date: 2021-09-02
Publication date: 2023-03-09
Also published as: CN116829665A; TWI824417B; KR20230107892A; CN116829665B; TW202323476A; JPWO2023032135A1; JP7109698B1; KR102656756B1

Abstract

The purpose of the present invention is to provide a heat-removable pressure-sensitive adhesive tape which is suitable for use in high-temperature heating steps and, when heated at a higher temperature after use in a heating step, can be significantly reduced in the adhesiveness of the pressure-sensitive adhesive layer to be easily removed without leaving an adhesive residue on the adherend, and which has excellent conformability to irregularities of adherends. The heat-removable pressure-sensitive adhesive tape comprises a substrate and a heat-removable pressure-sensitive adhesive layer disposed over at least one surface of the substrate, wherein the substrate has (a) a tensile strength at 100% elongation of 0.9 MPa or less, (b) a compression stress at 50% compression of 2.0 MPa or less, and (c) a value of tanδ at a maximum temperature during use of the heat-removable pressure-sensitive adhesive tape that is 100°C or higher, as obtained through a dynamic viscoelasticity measurement under the conditions of a frequency of 10 Hz, of 0.80 or less and the heat-removable pressure-sensitive adhesive layer 2 contains fine heat-expandable spheres having an expansion initiation temperature which is higher by at least 15°C than the maximum temperature during use, in an amount in the range of 6-50 parts by mass per 100 parts by mass of the pressure-sensitive adhesive component forming the heat-removable pressure-sensitive adhesive layer.

Description

Thermal peel adhesive tape

The present invention relates to a heat-peelable adhesive tape.

In various manufacturing processes including manufacturing processes of electronic parts and semiconductor parts, as an adhesive tape, thermally expandable microspheres are contained in the adhesive layer constituting the adhesive tape, and the adhesive force can be reduced and peeled off by heating. Techniques using heat-releasable adhesive tapes are known. In recent years, there has been an increasing number of types in which solder bumps or metal pins used for connection with substrate wiring portions are provided at electrode portions of semiconductor elements. In order to improve conformability to the surface of a semiconductor element having solder bumps and metal pins, Patent Document 1 proposes the use of a porous substrate as the substrate. Patent Document 1 discloses a heat-peelable double-sided pressure-sensitive adhesive sheet having a heat-peelable adhesive layer A on one side of a porous substrate and an adhesive layer B on the other side of the porous substrate, wherein the porous substrate has a density of 0.9 g/cm ³ or less and a tensile modulus of elasticity of 20 MPa or less, and is capable of processing a work piece having a surface with a maximum unevenness difference of 10 μm or more.

Further, Patent Document 2 discloses a heat-peelable pressure-sensitive adhesive sheet in which a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres is laminated on at least one side of a substrate via a rubber-like organic elastic layer. ing. This heat-peelable pressure-sensitive adhesive sheet is said to have excellent conformability to uneven surfaces by setting the rubber-like organic elastic layer and the heat-expandable pressure-sensitive adhesive layer to specific thicknesses and thickness ratios. Due to such followability, even if the adherend surface of the adherend is a rough surface, it exhibits sufficient adhesive strength, and even when used as a pressure-sensitive adhesive sheet for dicing semiconductor substrates having a rough surface such as sealing resin. It is said that chip flying is less likely to occur, and that it can be easily peeled off without applying stress to the adherend by heating after the completion of processing.

JP 2008-115272 A JP 2014-037539 A

Patent Documents

1 and 2 disclose a temperature of 100 to 250° C. as a heat treatment condition for peeling after processing. However, in the recent semiconductor manufacturing process, heat treatment is often performed in a state in which the adhesive sheet is adhered, and there is a need for a heat-peelable adhesive tape that does not peel off even at temperatures of 100°C or higher and that can be easily peeled off by heating. It has been demanded.

The present invention has been made in view of the above problems, and the adhesive tape used in the heating process of electronic parts and semiconductor parts can be suitably used in the heating process at high temperatures, and can be used at a higher temperature after use in the heating process. To provide a heat-peelable pressure-sensitive adhesive tape which is remarkably reduced in adhesiveness of an adhesive layer when heated, can be easily peeled off from an adherend without adhesive residue, and has excellent followability to irregularities of the adherend.

As a result of intensive studies by the present inventors to achieve the above object, a heat-peelable pressure-sensitive adhesive tape comprising a base material and a heat-peelable pressure-sensitive adhesive layer on at least one side of the base material,
of the substrate,
(a) a tensile strength at 100% elongation of 0.9 MPa or less;
(b) the compressive stress at 50% compression is 2.0 MPa or less,
(c) the value of tan δ at the maximum temperature of 100°C or higher when the heat-peelable pressure-sensitive adhesive tape is used, which is obtained by dynamic viscoelasticity measurement at a frequency of 10 Hz, is 0.80 or less;
The heat-peelable adhesive layer is
(d) A pressure-sensitive adhesive component 100 that contains thermally expandable globules having a foaming initiation temperature of +15° C. or more at the maximum temperature during use, and the content of the thermally expandable globules forms the thermally peelable adhesive layer. It was found that a heat-peelable pressure-sensitive adhesive tape, which is characterized by a range of 6 parts by mass or more and 50 parts by mass or less, is very effective for solving the above problems, and the present invention was completed. came to.

The heat-peelable pressure-sensitive adhesive tape of the present invention can be suitably used without being peeled off even in high-temperature processes in various manufacturing processes including manufacturing processes for electronic parts and semiconductor parts, and can be adhered by heating to a higher temperature after use in the same processes. It can be easily peeled off without adhesive residue, and has excellent conformability to unevenness of the adherend.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the example of the layer structure of the thermal peeling type adhesive tape which concerns on this invention.

Patent Documents

1 and 2 show examples in which the peeling temperature of the pressure-sensitive adhesive sheet is 100 to 120° C., but the operating temperature in that case is, of course, lower than 100° C., and there is no particular description. It is believed to be at room temperature (around 25°C). Therefore, there is no sufficient disclosure regarding use at high temperatures of 100° C. or higher and peeling at even higher temperatures. In terms of conformability to the unevenness of the adherend, it is preferable that the base material is a soft material. sometimes
Therefore, in the present invention, a material having both flexibility and heat resistance is used as the base material, so that it does not peel when used at a high temperature of 100 ° C. or higher, and can be easily peeled by heating to a higher temperature than the use temperature. Furthermore, the inventors have found that the object of the present invention can be achieved by combining a heat-peelable adhesive layer containing a predetermined amount of heat-expandable globules that start foaming at a temperature higher than the operating temperature.

The heat-peelable pressure-sensitive adhesive tape according to the present invention will be described in detail below.
The layer structure of the heat-peelable pressure-sensitive adhesive tape according to the present invention will be described with reference to the schematic cross-sectional view shown in FIG.

FIG. 1(A) shows a laminated structure of a base material 1 and a heat-peelable adhesive layer 2, which is the minimum layer structure, and FIG. 1(B) further shows a heat-peelable adhesive layer 2 of the base material 1 It shows a configuration in which a support layer 3 is laminated on the opposite surface of the surface. FIG. 1(C) shows an example in which an intermediate support layer 4 is provided on the surface of the substrate 1 on which the heat-peelable adhesive layer 2 is formed. 4 is added, the intermediate support layer 4 may be added to the layer structure of FIG. 1(A). FIG. 1(D) shows the layer structure of a double-sided adhesive tape in which adhesive layers are provided on both sides of a base material 1, a heat-peelable adhesive layer 2 is provided on one side, and a second adhesive layer 5 is provided on the other side. is provided. The second adhesive layer 5 can be either a normal adhesive layer or a heat-peelable adhesive layer. When the second adhesive layer 5 is a heat-peelable adhesive layer, the heating temperature for peeling may be the same as or different from that for the heat-peelable adhesive layer 2 .

A release film (not shown) can be provided on the adhesive surface of the heat-peelable adhesive layer and the surface of the substrate without the support layer to prevent adjacent layers from adhering when wound as a tape. . As the release film, one or both sides of a resin film such as polyester (eg, polyethylene terephthalate: PET) film subjected to release treatment can be used.

Each layer of the heat-peelable pressure-sensitive adhesive tape according to the present invention will be described below.
<Base material>
The substrate of the heat-peelable pressure-sensitive adhesive tape according to the present invention simultaneously satisfies the following conditions (a) to (c).
(a) a tensile strength at 100% elongation of 0.9 MPa or less;
(b) the compressive stress at 50% compression is 2.0 MPa or less,
(c) The value of tan δ is 0.80 or less at the maximum temperature of 100° C. or higher during use of the heat-peelable pressure-sensitive adhesive tape, which is obtained by dynamic viscoelasticity measurement at a frequency of 10 Hz.

The tensile strength of (a) was obtained by pulling a test piece (thickness 800 μm, width 25 mm, length 100 mm) at 23 ° C. and 50% RH at a speed of 300 mm / min with a distance between grips of 30 mm. Measure the tensile strength at 100%. A commercially available tensile tester can be used for the measurement. The tensile strength is 0.9 MPa or less, preferably 0.8 MPa or less.

The compressive stress in (b) is obtained by compressing a test piece (30 mm × 30 mm × 12 mm) at a speed of 10 mm/min in an environment of 23°C and 50% RH, and measuring the compressive stress at 50% deformation. A commercially available compression tester can be used for the measurement. The compressive stress is 2.0 MPa or less, preferably 1.5 MPa or less.

(c) tan δ (loss tangent) is a test piece (10 mm × 10 mm × 2 mm) using a dynamic viscoelasticity measuring device, while applying shear strain at a frequency of 10 Hz, at a heating rate of 10 ° C./min, - Storage modulus (G') and loss modulus (G'') are measured in the range of 50°C to 250°C. It is obtained by calculating tan δ. Here, the "maximum temperature of 100°C or higher when using the heat-peelable adhesive tape" means the maximum temperature of 100°C or higher at which the heat-peelable adhesive tape is actually used. The maximum temperature is set to a temperature that is 15° C. or more lower than the foaming start temperature of the thermally expandable globules contained in the thermally peelable adhesive layer. Therefore, even if the same base material is used, it means that the temperature at which tan δ is measured changes depending on the heat-peelable adhesive layer to be combined. The value of tan δ is 0.80 or less, preferably 0.70 or less.

As the base material, any material can be used as long as the above conditions (a) to (c) are satisfied. As the base resin (main component), any one of acrylic resin, silicone resin, and urethane resin can be used. is preferably From these resins, it is possible to satisfy the tensile strength and compressive stress specified by the above conditions (a) and (b), and the tan δ value of the above condition (c) is sufficient to be 0.80 or less. Materials with heat resistance can be selected.

The acrylic resin mainly contains (meth)acrylic acid alkyl ester as a monomer component, and an acrylic resin composition containing an acrylic copolymer resin can be obtained by combining this with a copolymerizable vinyl monomer.

Examples of (meth)acrylic acid alkyl esters include those having an alkyl ester portion having 1 to 20 carbon atoms, preferably having 1 to 12 carbon atoms, and those having 1 to 8 carbon atoms. more preferred. Specific examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) ) Tertiary butyl acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, isohexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, ethylhexyl (meth) acrylate, ( meth) nonyl acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, isododecyl (meth) acrylate, isobornyl (meth) acrylate, (meth) ) cyclohexyl acrylate and the like. These may be used alone or in combination of two or more. The (meth)acrylic acid alkyl ester accounts for 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and most preferably 80% by mass or more, in all the monomers.

Examples of copolymerizable vinyl-based monomers include carboxylic acid-containing (meth)acrylic monomers such as (meth)acrylic acid, β-carboxyethyl (meth)acrylate, itaconic acid, crotonic acid, maleic acid, and fumaric acid; ) 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2- (meth) acrylate Hydroxyhexyl, copolymerizable monomers containing hydroxyl group such as monoester of (meth)acrylic acid and polyethylene glycol or polypropylene glycol, (meth)acrylamide, N-alkyl-substituted (meth) such as N-isopropyl (meth)acrylamide acrylamide, N,N-dialkyl-substituted (meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, acryloylmorpholine, vinylpyridine, N-vinylpyrrolidone, (meth)acryl Nitrogen-containing acrylic monomers such as aminoethyl acid, dimethylaminoethyl (meth)acrylate and dimethylaminopropyl (meth)acrylate, vinyl monomers such as vinyl acetate, and the like. These may be used alone or in combination of two or more. Among them, it preferably contains acrylic acid, and acrylic acid is preferably contained in an amount of 1 to 20% by mass, more preferably 4.75 to 19% by mass, based on the total monomers.

The acrylic resin composition is obtained, for example, by polymerizing a (meth)acrylic acid alkyl ester and acrylic acid to prepare an acrylic syrup, and then adding other monomers and additives of the acrylic syrup to obtain an acrylic resin composition. can be done. This acrylic resin composition can be coated on a support having releasability and cured by UV curing or the like to prepare a base material.

Additives to the resin composition include hollow particles such as resin balloons and glass balloons, resin particles such as urethane beads, epoxy-based, isocyanate-based, and polyfunctional acrylate-based cross-linking agents, fillers, coloring agents, and antioxidants. , UV absorbers, surfactants, polymerization initiators, chain transfer agents, and other known additives can be added.

As for the silicone-based resin and urethane-based resin, it is sufficient to combine the raw materials and materials that can be used as the base material for the tape and select those that satisfy the above conditions (a) to (c). In the case of a silicone-based resin, it is preferable to use a platinum-based catalyst that promotes dehydration condensation of the siloxane compound. For urethane-based resins, it is preferable to use an epoxy-based or isocyanate-based cross-linking agent in combination.
Also, the base material may be selected from commercially available tape base materials that satisfy the above conditions (a) to (c). In that case, a product manufactured as a porous body such as urethane foam can also be used.

The thickness of the substrate is not particularly limited as long as it is a thickness that satisfies the conformability to unevenness according to the purpose of use, but is preferably 30 μm or more, more preferably 50 μm or more. Moreover, the upper limit of the thickness is preferably 2000 μm or less, more preferably 1000 μm or less.

<Heat peelable adhesive layer>
The heat-peelable adhesive layer according to the present invention contains an adhesive and heat-expandable globules, and the content of the heat-expandable globules is 6 parts per 100 parts by mass of the adhesive component forming the heat-peelable adhesive layer. It is in the range of 50 parts by mass or more and 50 parts by mass or less. The foaming start temperature of the heat-expandable globules is a temperature equal to or higher than the maximum temperature during use specified in the condition (c) above +15°C.

The heat-expandable microspheres used in the present invention include, for example, microspheres in which a substance such as isobutane, propane, and pentane that easily gasifies and expands upon heating is enclosed in an elastic shell. . The shell is often made of a hot-melt material or a material that breaks due to thermal expansion. Examples of substances forming the shell include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, and the like. Thermally expandable microspheres can be produced by conventional methods such as coacervation and interfacial polymerization. The foaming start temperature can be controlled mainly by the thickness of the shell, and the thicker the shell, the higher the foaming start temperature. For example, Matsumoto Microsphere (registered trademark) F and FN series, which have a shell thickness of 2 to 15 μm and an average particle size of 5 to 50 μm, are commercially available from Matsumoto Yushi Seiyaku Co., Ltd., and are preferably used. can be done. The thermally expandable spheres may be selected based on their expansion initiation temperature and expansion ratio.

As the adhesive component for forming the heat-releasable adhesive layer, any adhesive component that has sufficient adhesive force at the temperature of use and can be detached by heating at a high temperature by foaming the thermally expandable globules can be used. can also be used. Specific examples include (meth)acrylic copolymers, silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, and the like. In particular, from the viewpoint of adhesion to the substrate, it is also preferable to select the same type of resin as that constituting the substrate.

The (meth)acrylic copolymer can be used in combination with the vinyl monomer used for the base material. Among them, it is preferable that one or more structural units derived from a (meth)acrylic acid alkyl ester are used as a main component and a structural unit derived from acrylic acid is included. Further, the structural unit derived from acrylic acid is preferably contained in an amount of 2% by mass or more, more preferably 5% by mass or more, based on 100% by mass of all monomer units. If the acrylic acid-derived structural unit is 2% by mass or more based on 100% by mass of the total monomer units, even if the operating temperature is as high as 150°C, the step followability after heating is excellent. From the point of view of increasing the adhesive strength, it is also a preferred embodiment to use a hydroxyl group-containing acrylic acid ester together.

The content of the heat-expandable spheres is in the range of 6 parts by mass to 50 parts by mass, preferably 6 parts by mass to 40 parts by mass, based on 100 parts by mass of the adhesive component forming the heat-peelable adhesive layer. It is below. If the content of the heat-expandable globules is less than 6 parts by mass, the heat-releasable property due to the foaming of the heat-expandable globules cannot be exhibited sufficiently. On the other hand, when the content of the heat-expandable globules exceeds 50 parts by mass, the relative amount of the pressure-sensitive adhesive component decreases, making it impossible to obtain the desired pressure-sensitive adhesive strength.

Moreover, if the expansion start temperature of the thermally expandable globules is less than 15° C. relative to the maximum temperature during use specified in the above condition (c), the spheres may peel during use with heating, or the thermal peeling property may deteriorate, resulting in a decrease in heat release. After heating to the peeling temperature, when the temperature is returned to room temperature and peeled, the adhesive strength may not be sufficiently reduced, and peeling may become difficult.

Known additives can be added to the heat-peelable adhesive layer in addition to the adhesive component and the heat-expandable globules as long as they do not impair the effects of the present invention. Examples of additives include ultraviolet absorbers, antioxidants, colorants, and various fillers.

The thickness of the heat-peelable adhesive layer should be greater than the particle size of the heat-expandable spheres to be added, and should be within a range that does not impair the conformability of the substrate to irregularities. For example, the thickness may be selected within the range of 10 to 100 μm depending on the thickness of the substrate and the particle size of the thermally expandable globules. In the case of commercial products, the particle size of the thermally expandable spherules may be set by predicting the maximum particle size from the average particle size (catalog value), or by removing large particles by sieving or the like. , the mesh size of the sieve may be used as the set particle size.

<Support layer>
As shown in FIGS. 1(B) and 1(C), the heat-peelable pressure-sensitive adhesive tape according to the present invention has a resin film different from that of the substrate 1 on at least one side of the substrate 1 as a support layer 3 or an intermediate layer. It can be provided as a support layer 4 . The substrate used in the present invention may have tackiness, and if the thickness of the substrate is thin, sufficient strength may not be obtained. Therefore, it is preferable to provide a resin film as the support layer 3 or the intermediate support layer 4 .

The resin contained in this resin film preferably has lower tackiness than the substrate, has heat resistance, and is excellent in strength. and polycycloolefin resin. Among them, polyimide resin and polyethylene terephthalate (PET) are preferred.

The thickness of the support layer 3 is preferably 20 μm or more, more preferably 40 μm or more, from the viewpoint of imparting moderate strength. The upper limit may be set in consideration of the thickness of the substrate and the thickness of the entire heat-peelable pressure-sensitive adhesive tape. The thickness of the intermediate support layer 4 is preferably 20 μm or less, more preferably 15 μm or less, because the thicker the intermediate support layer 4 , the more difficult it is to obtain the step followability of the base material. Although there are no particular restrictions on the thickness, the thickness is preferably 1 μm or more, more preferably 5 μm or more, in consideration of the provision of the intermediate support layer 4 .

<Double-sided adhesive tape>
The heat-peelable pressure-sensitive adhesive tape according to the present invention, as shown in FIG. can do. At this time, the thermally releasable adhesive layer 2 may be called the first adhesive layer as opposed to the second adhesive layer 5 . The first adhesive layer is the heat-releasable adhesive layer according to the present invention, but the second adhesive layer may be either the heat-releasable adhesive layer or a normal adhesive layer. When the second adhesive layer is a heat-peelable adhesive layer, it may be the same as or different from the heat-peelable adhesive layer of the first adhesive layer. That is, it may be a heat-peelable adhesive layer that is thermally peeled off at a higher temperature or lower temperature than the first adhesive layer. By doing so, it is possible to set the temperature for peeling off the members attached to the respective surfaces of the double-sided adhesive tape.

<How to use the heat peelable adhesive tape>
The heat-peelable pressure-sensitive adhesive tape according to the present invention is used for the manufacturing process of a member having an uneven surface. A semiconductor substrate, an electronic component, or the like can be given as examples of the member having an uneven surface.
In particular, the adherend targeted by the present invention is a member used in manufacturing that requires a temperature of 100° C. or higher. For example, a temperature of about 150 to 200° C. may be applied in processes such as solder reflow. In the present invention, the maximum temperature reached in such a manufacturing process is defined as the maximum temperature during use of the heat-peelable pressure-sensitive adhesive tape (usage temperature).
Since the thermally expandable globules contained in the thermally releasable adhesive layer have a foaming start temperature in a temperature range 15°C or more higher than the usage temperature, they do not foam at the usage temperature and maintain adhesive strength. can be done.
When the adhesive layer is subsequently peeled off, heating to a temperature equal to or higher than the foaming start temperature causes the thermally expandable globules to expand and foam, resulting in the action of separating the thermally peelable pressure-sensitive adhesive layer from the adherend. The heating temperature at this time is called the thermal peeling temperature, and as described above, it is sufficient if the temperature is equal to or higher than the foaming start temperature. Therefore, the thermal peeling temperature is preferably 30° C. or higher, more preferably 40° C. or higher, than the foaming start temperature. Also, the time for thermal detachment can be appropriately set depending on the temperature difference between the thermal detachment temperature and the foaming start temperature, the shell material and shell thickness of the thermally expandable spherules, and the type of the contained vapor.
When peeling off, it is preferable to cool the adhesive before peeling, in order to avoid so-called adhesive deposits, that is, residues of thermally expandable spheres and adhesive residues remaining on the adherend. The peeling temperature is lower than the working temperature, preferably 100° C. or lower, more preferably 50° C. or lower, and the peeling may be performed after cooling to room temperature (around 25° C.).

The present invention will be specifically described below with reference to examples, but the present invention is not limited only to these examples. In addition, "parts" or "%" in Examples and Comparative Examples indicate values based on mass unless otherwise specified.

[Substrate preparation method]
-Acrylic syrup preparation method The composition shown in Table 1 is put into a flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet, and an ultraviolet irradiation device (manufactured by Panasonic Corporation: product name "Aicure UP50") is placed in a nitrogen atmosphere. ”), the acrylic syrup is obtained by irradiating with ultraviolet rays for 8 to 12 minutes at an irradiation intensity of 800 to 1,200 mW/cm ² (manufactured by Itec System Co., Ltd.: measured using a photometer UVM-100) for photopolymerization. rice field.

Preparation of Acrylic Base Material Materials having the compositions shown in Table 2 were added to each of the obtained syrups 1 to 4 and uniformly mixed to obtain a base composition.
The substrate composition was applied to the release-treated surface of a 50 μm-thick PET release film (manufactured by Fujimori Kogyo Co., Ltd., product name “Film Biner (registered trademark) KF#50”) one side of which was subjected to silicone release treatment. The release-treated surface of the release-treated PET release film was placed on the base composition, and a composition sandwiched between two PET release films was produced. A fluorescent lamp (manufactured by Toshiba: FL20S W) with an irradiation intensity of 3.0 to 5.0 mW/cm ² is irradiated from both sides for 30 seconds to 2 minutes depending on the coating thickness to cure the base composition, and the acrylic base material. got The thickness of the acrylic base material was adjusted to 50 μm to 800 μm.

Details of the materials in Table 2 are as follows:
・ Resin balloon: Product name “F-80DE” manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.
・ Glass balloon: Product name “34P30T” manufactured by Potters Barrotini
・ Urethane beads: Product name “Art Pearl P-800T” manufactured by Negami Kogyo Co., Ltd.
・α-hydroxyacetophenone: trade name “Omnirad 1173” manufactured by IGM Resins

[Evaluation of physical properties of base material]
Tensile strength, compressive stress, and tan δ of the obtained base material were measured by the following methods.
・ Tensile strength of base material A base material with a thickness of 800 μm, a width of 25 mm, and a length of 100 mm was measured using a tensile tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.: Strograph V-1C) at 23 ° C., 50% RH, between grips. It was pulled under conditions of a distance of 30 mm and a test speed of 300 mm/min, and the tensile strength at 100% elongation was measured.

- Compressive stress of base material A laminate having a thickness of 12 mm was formed by stacking base materials of 30 mm square. This laminate was compressed using a compression tester (manufactured by Shimadzu Corporation: AG-50kNX Plus) under the conditions of 23° C., 50% RH, and a test speed of 10 mm/min, and the compressive stress at 50% deformation was measured.

・tan δ of base material
A laminate having a thickness of 2 mm was formed by stacking substrates of 10 mm square. Using a dynamic viscoelasticity measuring device (manufactured by TA Instruments: ARES-G2), this laminate is subjected to a temperature increase rate of 10 ° C./min while applying a shear strain at a frequency of 10 Hz, in the range of -50 ° C. to 250 ° C. The storage elastic modulus (G′) and loss elastic modulus (G″) were measured at . From the storage elastic modulus (G′) and loss elastic modulus (G″), the loss tangent tan δ at each temperature was calculated by the following formula: bottom.
tan δ = loss modulus (G″)/storage modulus (G′)
Table 3 shows the above results. A commercially available silicone base material and a urethane base material were also evaluated in the same manner.

The substrate names in Table 3 are as follows.
Si: silicone base material, trade name "Unicon UT-30", manufactured by Kotec PU: urethane base material, trade name "PureCell (registered trademark) UC150PR" manufactured by INOAC Corporation In the above, the colored parts are the conditions according to the present invention. are shown, and the same applies to the following tables. The base material AS9 does not satisfy the conditions (a) and (b) according to the present invention, and the base material AS10 does not satisfy the condition (c) according to the present invention. The remaining AS1 to AS8, Si, and PU substrates are substrates that can be used at any operating temperature of 100 to 180°C.

[Method for preparing heat-peelable adhesive layer]
- Base polymer (acrylic copolymer) preparation method Acrylic copolymers Ac1 to Ac4 having the compositions shown in Table 4 were polymerized.
The compounding ratio of each component in Table 4 indicates the ratio when the total is 100 parts. Table 3 also shows the theoretical Tg and weight average molecular weight (Mw) of each acrylic copolymer for reference. The theoretical Tg is a value calculated by the FOX formula, and can be adjusted by appropriately selecting the composition of the acrylic monomer. Moreover, this weight average molecular weight (Mw) is a value measured by the GPC method, and the weight average molecular weight of the acrylic copolymer converted to standard polystyrene was measured using the following measuring apparatus and conditions.
・ Apparatus: LC-2000 series (manufactured by JASCO Corporation)
・Column: ShodexKF-806M×2, ShodexKF-802×1 ・Eluent: Tetrahydrofuran (THF)
・Flow rate: 10 mL/min ・Column temperature: 40°C
・Injection volume: 100 μL
・Detector: Refractometer (RI)
・Measurement sample: A solution obtained by dissolving an acrylic polymer in THF to prepare a solution having an acrylic polymer concentration of 0.5%, and filtering the solution with a filter to remove dust.

The weight average molecular weight (Mw) is determined by the type and amount of the polymerization initiator (for example, 0.1 part of lauryl peroxide per 100 parts of the acrylic monomer) and the type and amount of the chain transfer agent when the acrylic copolymer is polymerized. (eg, 0.1 part of n-dodecanethiol with respect to 100 parts of acrylic monomer), polymerization initiation concentration (eg, 50%), etc. can be adjusted as appropriate.

[Adhesive composition preparation method]
Materials having the composition shown in Table 5 below were added to 100 parts of the solid content of each adhesive and uniformly mixed to obtain a heat-peelable adhesive composition.

In Table 5, the materials used are as follows:
・ Silicone adhesive: Shin-Etsu Chemical Co., Ltd., trade name "KR-3700" and "X-40-3306" mixture (mass ratio 80/20)
・Polyester adhesive: manufactured by Mitsubishi Chemical Corporation, trade name “NP-110S50”
・ FN-190SSD: Trade name “Matsumoto Microsphere (registered trademark) FN-190SSD” manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., foaming start temperature 171 ° C.
・F-260D: Trade name “Matsumoto Microsphere (registered trademark) F-260D”, manufactured by Matsumoto Yushi Seiyaku Co., Ltd., foaming start temperature 198 ° C.
・ FN-100MD: Trade name “Matsumoto Microsphere (registered trademark) FN-100MD” manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., foaming start temperature 119 ° C.
・F-50D: Trade name “Matsumoto Microsphere (registered trademark) F-50D”, manufactured by Matsumoto Yushi Seiyaku Co., Ltd., foaming start temperature 112 ° C.
・ E-5CM: trade name, manufactured by Soken Chemical Co., Ltd., epoxy-based cross-linking agent, solid content 5%
・ L-45E: trade name, manufactured by Tosoh Corporation, isocyanate cross-linking agent, solid content 45%
・ CAT-PL-50T: trade name, manufactured by Shin-Etsu Chemical Co., Ltd., platinum-based catalyst ・ Irganox 1010: trade name, manufactured by BASF, hindered phenolic antioxidant

Examples 1-22, Comparative Examples 1-4
[Adhesive tape production method]
The pressure-sensitive adhesive composition obtained above is coated on a PET release film having a thickness of 50 μm (manufactured by Fujimori Kogyo Co., Ltd., product name “Film Biner (registered trademark) KF #50”) that has been subjected to silicone release treatment. was applied so as to have a thickness of 50 μm. Next, it was placed in a dryer (PHH-201, manufactured by Espec Co., Ltd.) to dry the diluted solvent at 50 to 110° C. and to carry out a cross-linking reaction to form a thermally expandable adhesive layer. Peel off the PET release film on both sides of the substrate, transfer the thermally expandable adhesive layer to one side of the substrate, and attach a 50 μm thick PET film (manufactured by Toray Industries, Inc., trade name “Lumirror #50-S10”) to the other side. They were laminated together and cured at 40° C. for 3 days to obtain an adhesive tape. A heat-releasable adhesive tape having a layer structure shown in FIG. In addition, the physical properties of the substrate measured by the following methods, the foaming start temperature of the thermally expandable globules, the test temperature based on it (use temperature of the adhesive tape), the thermal peeling temperature, and the tan δ value of the substrate at the test temperature are shown. 6 is shown.

[Evaluation of physical properties of adhesive layer]
-Method for measuring expansion start temperature of thermally expandable microspheres The expansion start temperature of thermally expandable microspheres can be obtained by using a thermal analyzer TMA (manufactured by Hitachi High-Tech Science Co., Ltd.: TMA7100). The foaming start temperature of the thermally expandable spheres was analyzed by putting the thermally expandable spheres into a 5 mmφ aluminum pan, covering it with an inner lid, and using compression mode (L assembly control, heating rate: 10°C/min). The temperature at which the displacement in the vertical direction of the measuring terminal began to rise was defined as the temperature.

In the above Table 6, the step followability was evaluated for the example in which the test temperature was 150°C.
- Level difference followability A polyimide tape (manufactured by Teraoka Seisakusho Co., Ltd., product name "No. 6544") having a thickness of 90 µm and a size of 5 mm x 30 mm was attached to a glass plate to prepare glass with a step difference having a pseudo step for testing. The heat-expandable adhesive layer side of a 20 mm square adhesive tape was placed on a stepped glass, and a 5 kg rubber roller was reciprocated once at 300 mm/min to prepare an adhesive test piece. Using a microscope (manufactured by Keyence Corporation: VHX-6000), the width of bubbles generated around the step was measured at three points at intervals of 5 mm, and the average value was calculated.
The test piece was placed in a dryer and heated at a test temperature of 150° C. for 30 minutes, and then the cell width was similarly calculated.
The step followability was evaluated according to the following criteria.
A: Bubble width less than 1 mm B: Bubble width 1 mm or more and less than 5 mm C: Bubbles were connected or the adhesive tape was peeled off from the test piece.

In Comparative Example 1, it was confirmed that the AS9 base material, which does not satisfy the above conditions (a) and (b) of the present invention, is used as the base material, so that the flexibility is low and the step followability is poor. As shown in Examples 2 to 4, it can be seen that the thickness of the base material has almost no effect.

Heat Resistance The influence of the substrate tan δ under the condition (c) was evaluated. Specifically, in an example of an acrylic base material with a base thickness of 200 μm, the adhesive tape is cut into 20 mm squares, and the thickness (manufactured by Peacock: dial thickness gauge G-6), dimensions (manufactured by Keyence: VHX-6000 ) was measured. A 20 mm square adhesive tape is placed on an aluminum plate (A1050P) with a thickness of 1.0 mm and 50 mm x 125 mm, and a float glass plate (R 3202) with a weight of 20 g (thickness of 2.8 mm and 50 mm x 60 mm) is placed on the adhesive tape. put it on top. This was placed in a dryer (Espec: PHH-201) and heated at the test temperature shown in Table 5 for 30 minutes, and then the thickness and dimensions of the adhesive tape were measured.
The thickness was measured at the center of the tape, and the dimension was measured at 3 points each in the width direction and the length direction of the tape at intervals of 5 mm, 6 points in total, and the average value was calculated.
Heat resistance was evaluated according to the following criteria.
A: Thickness reduction before and after heating is less than 15%, or dimensional change is less than 0.5 mm C: Thickness reduction before and after heating is 15% or more, or dimensional change is 0.5 mm or more Table 8 shows the results.

As is clear from Table 8 above, deformation during processing could be suppressed by tan δ being 0.80 or less at the processing temperature of the base material. Comparative Example 2, in which tan δ exceeds 0.80, showed a large dimensional change. In addition, in Example 11 using a silicone base material and Example 12 using a urethane base material, tan δ was 0.80 or less, and deformation during processing was suppressed.

Next, the adhesive strength and heat peelability were evaluated.
- Initial Adhesive Strength An adhesive tape having a width of 10 mm and a length of 100 mm was attached to an aluminum plate (A1050P) having a thickness of 1.0 mm and a size of 50 mm x 125 mm. A 5 kg roller was reciprocated once at a speed of 300 mm/min for pressure bonding, and then left at 23° C. and 50% RH for 20 to 40 minutes. Using a tensile tester, the peel strength of the adhesive layer was measured at 23° C., 50% RH, a test speed of 300 mm/min, and a peel angle of 90°, and was defined as the initial adhesive strength.

Adhesive strength after heating The adhesive tape was laminated and pressure-bonded in the same manner as the measurement of the initial adhesive strength, and then placed in a dryer and heated at the test temperature shown in Table 6 for 30 minutes. Removed from the dryer and left at 23°C, 50% RH for 20 to 40 minutes, then using a tensile tester, measure the peel strength of the tape at 23°C, 50% RH, test speed of 300 mm/min, and peel angle of 90°. bottom.

・Heat peelability After heating, heat at the same test temperature as for adhesive strength, remove from the dryer and allow to stand at 23 ° C., 50% RH for 20 to 40 minutes. and heated for 5 minutes. It was taken out from the dryer and allowed to stand at 23° C. and 50% RH for 20 to 40 minutes. At that time, the sample that was naturally peeled was designated as "A". For those that did not spontaneously peel off, the peel strength was evaluated in the same manner as the adhesive strength described above, and "B" was given when the peel strength was less than 1.0 N/10 mm, and "C" was given when it was 1.0 N/10 mm or more. Table 9 shows the results.

Example 23
On the surface opposite to the surface on which the thermally expandable adhesive layer of the base material is formed, a PET release film with a thickness of 50 μm that has been subjected to silicone release treatment instead of the PET film as the support layer (manufactured by Fujimori Kogyo Co., Ltd., product name “Film Binner A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, except that it was changed to (registered trademark) KF#50"). The layer structure excluding the PET release film is shown in FIG. 1(A).
In the step followability test, the PET release film was peeled off and heated. ”) was pasted and measured.

Example 24
An adhesive tape was obtained in the same manner as in Example 1 except that the PET film on the opposite side of the thermally expandable adhesive layer was changed to a 50 μm thick PI film (manufactured by Toray DuPont, product name “Kapton 100H”).

Example 25
The pressure-sensitive adhesive composition AD1 was applied onto an intermediate support layer made of a 12 μm-thick PET film (manufactured by Toray Industries, Inc., product name “Lumirror #12-S10”) so that the thickness of the pressure-sensitive adhesive layer was 50 μm. Then, it was placed in a dryer to dry the diluent solvent at 50 to 110° C. and to cause a cross-linking reaction to form a thermally expandable adhesive layer. The PET release film on one side of the acrylic base material 1 was peeled off, and the base material was attached to the PET film surface of the PET film coated with the thermally expandable adhesive layer. The PET film on the other side of the substrate was peeled off, a PET film with a thickness of 50 μm was attached, and the substrate was cured at 40° C. for 3 days to obtain an adhesive tape having a layer structure shown in FIG. 1(C).

Example 26
The pressure-sensitive adhesive composition AD1 is applied to a PET release film having a thickness of 50 μm (manufactured by Fujimori Kogyo Co., Ltd., product name “Film Biner (registered trademark) KF#50”) that has been subjected to silicone release treatment, and the adhesive layer is coated so that the thickness of the adhesive layer is 50 μm. was applied to Then, it was placed in a drier to dry the diluted solvent at 50 to 110° C., and cross-linking reaction was performed to prepare two films each having a heat-expandable adhesive layer. The PET release film on one side of the substrate was peeled off, and the first thermally expandable adhesive layer was transferred to form the first adhesive layer. On the first adhesive layer, the above-described PET release film was laminated on the release-treated surface side. Furthermore, the PET release film on the other side of the substrate is peeled off, the second thermally expandable adhesive layer is transferred to form the second adhesive layer, and the PET release film is released on the second adhesive layer. It was pasted together on the mold-processed surface side. After that, it was cured at 40° C. for 3 days to obtain an adhesive tape.
In the step followability test, the PET release film on the surface opposite to the adhesive surface was also peeled off and heated, and when measuring the adhesive force, the PET release film on the surface opposite the adhesive surface was peeled off. (manufactured by Toray Industries, Inc., product name “Lumirror #50-S10”) was attached and measured.
Table 10 shows the results of Examples 23 to 26 above.

As is clear from Table 10 above, even if the tape composition is different, step followability and thermal peelability can be expressed. Moreover, by providing a thermally expansible pressure-sensitive adhesive layer on both sides, it is possible to impart thermal releasability to both sides.

REFERENCE SIGNS LIST 1 substrate 2 heat-peelable adhesive layer 3 support layer 4 intermediate support layer 5 second adhesive layer

Claims

A heat-peelable pressure-sensitive adhesive tape comprising a base material and a heat-peelable pressure-sensitive adhesive layer on at least one side of the base material,
of the substrate,
(a) a tensile strength at 100% elongation of 0.9 MPa or less;
(b) the compressive stress at 50% compression is 2.0 MPa or less,
(c) the value of tan δ at the maximum temperature of 100°C or higher when the heat-peelable pressure-sensitive adhesive tape is used, which is obtained by dynamic viscoelasticity measurement at a frequency of 10 Hz, is 0.80 or less;
The heat-peelable adhesive layer is
(d) A pressure-sensitive adhesive component 100 that contains thermally expandable globules having a foaming initiation temperature of +15° C. or more at the maximum temperature during use, and the content of the thermally expandable globules forms the thermally peelable adhesive layer. A heat-peelable pressure-sensitive adhesive tape, characterized in that the content is in the range of 6 parts by mass or more and 50 parts by mass or less based on the mass parts.
The heat-peelable pressure-sensitive adhesive tape according to claim 1, wherein the base material is a resin base material containing at least one resin selected from the group consisting of acrylic resins, silicone resins, and urethane resins as a main component.
The heat-peelable pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive component contains a (meth)acrylic copolymer as a main component.
The (meth)acrylic copolymer contains structural units derived from acrylic acid, and the content of the structural units derived from acrylic acid is the total monomer units constituting the (meth)acrylic copolymer. The heat-peelable pressure-sensitive adhesive tape according to claim 1, which is 2% by mass or more with respect to 100% by mass.
The heat-peelable pressure-sensitive adhesive tape according to claim 1, wherein a resin film different from the base material is provided as a support layer on at least one side of the base material.
The resin according to claim 5, wherein the resin contained in the resin film is at least one selected from the group consisting of polyimide resin, fluororesin, polyester resin, polyetheretherketone resin, polyphenylene sulfide resin and polycycloolefin resin. Thermally removable adhesive tape.
The heat-peelable adhesive layer formed on one surface side of the base material is a first adhesive layer, and the second adhesive layer is provided on the other surface side different from the one surface of the base material. 2. The heat-peelable pressure-sensitive adhesive tape according to claim 1, wherein the second pressure-sensitive adhesive layer has the same or different composition as the first pressure-sensitive adhesive layer.
The heat-peelable pressure-sensitive adhesive tape according to any one of claims 1 to 7, characterized by being used for the manufacturing process of a member having an uneven surface.